{
  "cveId": "CVE-2026-23450",
  "url": "https://patchblox.com/security/cve/CVE-2026-23450",
  "summary": "CVE-2026-23450 is fixed in 12 products on 1 platform, first by DEBIAN-CVE-2026-23450, released April 3, 2026. It is not reported as exploited. Patch Radar priority: Urgent.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  net/smc: fix NULL dereference and UAF in smc_tcp...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()  Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1].  smc_tcp_syn_recv_sock() is called in the TCP receive path (softirq) via icsk_af_ops-\u003Esyn_recv_sock on the clcsock (TCP listening socket). It reads sk_user_data to get the smc_sock pointer. However, when the SMC listen socket is being closed concurrently, smc_close_active() sets clcsock-\u003Esk_user_data to NULL under sk_callback_lock, and then the smc_sock itself can be freed via sock_put() in smc_release().  This leads to two issues:  1) NULL pointer dereference: sk_user_data is NULL when    accessed. 2) Use-after-free: sk_user_data is read as non-NULL, but the    smc_sock is freed before its fields (e.g., queued_smc_hs,    ori_af_ops) are accessed.  The race window looks like this (the syzkaller crash [1] triggers via the SYN cookie path: tcp_get_cookie_sock() -\u003E smc_tcp_syn_recv_sock(), but the normal tcp_check_req() path has the same race):    CPU A (softirq)              CPU B (process ctx)    tcp_v4_rcv()     TCP_NEW_SYN_RECV:     sk = req-\u003Ersk_listener     sock_hold(sk)     /* No lock on listener */                                smc_close_active():                                  write_lock_bh(cb_lock)                                  sk_user_data = NULL                                  write_unlock_bh(cb_lock)                                  ...                                  smc_clcsock_release()                                  sock_put(smc-\u003Esk) x2                                    -\u003E smc_sock freed!     tcp_check_req()       smc_tcp_syn_recv_sock():         smc = user_data(sk)           -\u003E NULL or dangling         smc-\u003Equeued_smc_hs           -\u003E crash!  Note that the clcsock and smc_sock are two independent objects with separate refcounts. TCP stack holds a reference on the clcsock, which keeps it alive, but this does NOT prevent the smc_sock from being freed.  Fix this by using RCU and refcount_inc_not_zero() to safely access smc_sock. Since smc_tcp_syn_recv_sock() is called in the TCP three-way handshake path, taking read_lock_bh on sk_callback_lock is too heavy and would not survive a SYN flood attack. Using rcu_read_lock() is much more lightweight.  - Set SOCK_RCU_FREE on the SMC listen socket so that   smc_sock freeing is deferred until after the RCU grace   period. This guarantees the memory is still valid when   accessed inside rcu_read_lock(). - Use rcu_read_lock() to protect reading sk_user_data. - Use refcount_inc_not_zero(\u0026smc-\u003Esk.sk_refcnt) to pin the   smc_sock. If the refcount has already reached zero (close   path completed), it returns false and we bail out safely.  Note: smc_hs_congested() has a similar lockless read of sk_user_data without rcu_read_lock(), but it only checks for NULL and accesses the global smc_hs_wq, never dereferencing any smc_sock field, so it is not affected.  Reproducer was verified with mdelay injection and smc_run, the issue no longer occurs with this patch applied.  [1] https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9",
  "published": "2026-04-03T16:16:31Z",
  "severity": "critical",
  "cvss": 9.8,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00461,
  "epssPercentile": 0.40216,
  "priority": "Urgent",
  "priorityTier": 2,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "kernel-64kb",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.55.1",
      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
      "product": "kernel-azure",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.55.1",
      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default",
      "release": "sles 15.6",
      "fixedVersion": "6.4.0-150600.23.112.1",
      "fix": "SUSE-SU-2026:2195-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2195-1",
      "released": "2026-07-01T08:17:32Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.55.1",
      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default-base",
      "release": "sles 15.6",
      "fixedVersion": "6.4.0-150600.23.112.1.150600.12.52.1",
      "fix": "SUSE-SU-2026:2195-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2195-1",
      "released": "2026-07-01T08:17:32Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default-base",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.55.1.150700.17.33.1",
      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
      "product": "kernel-docs",
      "release": "sles 15.6",
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      "fix": "SUSE-SU-2026:2195-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2195-1",
      "released": "2026-07-01T08:17:32Z"
    },
    {
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      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
      "product": "kernel-livepatch-SLE15-SP6_Update_26",
      "release": "sles 15.6",
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      "fix": "SUSE-SU-2026:2195-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2195-1",
      "released": "2026-07-01T08:17:32Z"
    },
    {
      "platform": "linux",
      "product": "kernel-livepatch-SLE15-SP7_Update_15",
      "release": "sles 15.7",
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      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
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      "fix": "SUSE-SU-2026:2195-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2195-1",
      "released": "2026-07-01T08:17:32Z"
    },
    {
      "platform": "linux",
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      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.55.1",
      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
      "product": "kernel-source",
      "release": "sles 15.6",
      "fixedVersion": "6.4.0-150600.23.112.1",
      "fix": "SUSE-SU-2026:2195-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2195-1",
      "released": "2026-07-01T08:17:32Z"
    },
    {
      "platform": "linux",
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      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.55.1",
      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
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      "release": "sles 15.6",
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      "fix": "SUSE-SU-2026:2195-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2195-1",
      "released": "2026-07-01T08:17:32Z"
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    {
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    },
    {
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      "fix": "SUSE-SU-2026:2238-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-2238-1",
      "released": "2026-06-30T10:03:11Z"
    },
    {
      "platform": "linux",
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      "release": "Debian 12.15 (bookworm)",
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      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-23450",
      "released": "2026-04-03T16:16:31Z"
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    {
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    {
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      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-23450",
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    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}